The present invention relates to a system and method for waste water treatment wherein energy saving and reduction of suspended solids by digestion can be achieved. The present invention also relates to a waste-water treatment system constituted by solely using an attachment filter having a sedimentation section or combining an attachment filter and a rapid filter. The present invention further relates to a waste-water treatment system capable of performing a highly efficient treatment of organic matters and an advanced treatment of suspended solids (two-stage filtration).
In an age of global environmental protection, an important issue for any company is how to reduce various wastes generated in its operation centers.
Furthermore, reduction of waste has become a recent important issue from viewpoints of recent reduction of the number of disposal sites and recent efforts towards zero emission by various companies.
Similarly, an issue of sludge generated from waste-water treatment equipment is also being grappled with in various manners.
Solids suspended in waste water is filtered until its amount falls in a range of regulation values or removed by coagulating sedimentation using a chemical or the like. Therefore, sludge is generated after the treatment.
Conventionally, a rapid filter as a filter employed in a common waste-water treatment system is composed of a water-conveying pump and backwash pump. Power consumption was high, in particular, due to a long running time of the water-conveying pump.
However, energy saving measures for the equipment has become so important today that it has become necessary to thoroughly plan and implement energy saving in the waste-water treatment system as well.
However, as long as the rapid filter is used, energy saving measures relevant to pumps for use in the rapid filter have approached their limit, thereby making energy saving substantially difficult. Furthermore, the rapid filter does not have a function for digesting and reducing suspended solids in waste water.
On the other hand, a biological filter consumes a relatively little electrical energy. However, there were cases microorganisms exfoliated from the biological filter deteriorated water quality.
One example of such conventional techniques having a biological filter (Japanese Patent Laid-Open Publication HEI 9-314163) is described below. This conventional technique provides a waste-water treatment system wherein waste water is introduced into a charcoal tank filled with charcoal for treatment and then the waste water from this charcoal tank is introduced into an activated carbon tower filled with activated carbon for treatment.
Since microorganisms are propagated in both the charcoal in the charcoal tank and the activated carbon in the activated carbon tower, these are called biologically activated charcoal and biologically activated carbon, respectively. This two-stage treatment by the biologically activated charcoal and the biologically activated carbon has a merit that a backwash process and a reproduction process in the activated carbon tower are not required. Consequently, the life of the activated carbon can be substantially extended.
Since a biofilm is also formed on the surface of the biologically activated charcoal and waste water constantly circulates in a water tank by aeration, aerobic biofilm filtration is performed by the biologically activated charcoal. That is, biological filtration is constantly performed. Although charcoal is also a packing material, anaerobic digestion of sludge by microorganisms cannot be expected since the central portion does not have a considerably large anaerobic portion unlike a vinylidene chloride filler. Furthermore, since charcoal is not negatively charged, a large amount of suspended floc and suspended microorganisms cannot be attached and held to charcoal unlike a vinylidene chloride filler. Therefore, the above conventional technique (Japanese Patent Laid-Open Publication HEI 9-314163) does not have a remarkable effect on reduction of the generated sludge.
Another example of conventional techniques (Japanese Patent Laid-Open Publication HEI 10-314778) is described below. This conventional technique provides a waste-water treatment system wherein suspended solids are captured and removed and decomposition of organic matters by microorganisms can be sufficiently performed. Specifically, this system is constituted by an oxygen supply tank having a diffusing pipe installed at a bottom section thereof, a carrier attachment filter tank filled with fillers and a wash water discharge pump tank equipped with a wash water discharge pump. Furthermore, a diffusing pipe is installed at the bottom section of the carrier attachment filter tank and granular carriers as fillers are filled thereabove.
In this waste-water treatment system, suspended solids can be attached and removed or organic matters in waste water can be removed by microorganisms propagated on the packing material. However, since there is no anaerobic portion, digestion of attached suspended solids or propagated microorganisms (that is, reduction of generated sludge) cannot be expected. Furthermore, since a rapid filter is not installed after the carrier attachment filter tank, a sufficient measure is not taken when sludge exfoliates from the carrier attachment filter tank.
Accordingly, the object of the present invention is to provide a system and method for waste water treatment that can save energy and reduce waste.
In order to achieve the above object, there is provided a waste-water treatment system comprising an attachment filter having a packing material to which suspended solids are attached and a sedimentation section in a bottom section thereof, wherein
solids suspended in waste water are treated by sedimenting the solids attached to the packing material in the sedimentation section.
In the present invention, solids suspended in waste water are attached to the packing material in the attachment filter and then particle sizes are increased (particles are stacked to each other and are enlarged). Then, the solids attached in an anaerobic state are digested and reduced. Furthermore, sludge generated from the suspended solids is sedimented, separated and removed in the same attachment filter tank. In the present invention, since solids suspended in waste water can be treated by the attachment filter having a sedimentation section, solids suspended in waste water can be filtered without consuming a large amount of electrical energy. Furthermore, the generated sludge is sedimented in the sedimentation section and removed from this sedimentation section. Thus, waste water can be treated.
When microorganisms are attached and propagated on the packing material provided in the attachment filter, a function for decomposing organic matters is provided and the packing material itself has an attachment action. Therefore, a function for attaching solids suspended in waste water to this packing material for filtration is provided.
The above xe2x80x9cattachment filterxe2x80x9d means a filter wherein suspended solids such as a floc suspended in waste water or suspended microorganisms are attached and captured by a packing material carrying negative charges. The xe2x80x9cattachment filter having a sedimentation sectionxe2x80x9d means a device having both sedimenting and attaching functions.
In one embodiment of the present invention, the sedimentation section has a sludge collecting function for collecting sedimented sludge.
According to the above embodiment, the sedimentation section has a sludge collecting function. Therefore, after increase of particle sizes, specific gravity is changed by digestion and thereby sedimented sludge can be efficiently collected in the sedimentation section. Therefore, waste water in which a large amount of sludge is generated can also be treated by the sedimentation section having a sludge collecting function.
In one embodiment of the present invention, a rapid filter is installed in a subsequent stage of the attachment filter; and
solids suspended in waste water are treated first in the attachment filter and then filtered by the rapid filter.
According to the above embodiment, solids suspended in waste water are treated first in the attachment filter and then filtered by the rapid filter. Therefore, the filtering precision can be improved by performing two-stage filtration as compared with one-stage filtration. That is, there is provided a system capable of reducing suspended solids, that is, sludge, and reliably removing the suspended solids, which is digested and reduced, at the same time (combination of an attachment filter having a sedimentation section and a rapid filter) According to the present invention, precise filtration can be reliably performed at all times. Furthermore, genesis sludge capacity is small since the attachment filter is in the previous stage, wherein sludge is digested.
In one embodiment of the present invention, a rapid filter is installed in parallel to the attachment filter; and
solids suspended in waste water are treated in the attachment filter and the rapid filter in parallel.
In this embodiment, since solids suspended in waste water are treated by (1) an attachment filter having a sedimentation section and (2) a rapid filter, which are disposed in parallel, the filters can be selected and operated according to target water quality (suspended solids).
Since the suspended solid concentration in treated water obtained from the rapid filter is lower than the suspended solid concentration in treated water obtained from the attachment filter having a sedimentation section, the target suspended solid concentration after treatment can be set by adjusting inflow of waste water into the attachment filter and the rapid filter.
In one embodiment of the present invention, the attachment filter has a radial ring-shaped thread structure composed of a plurality of radially extending ring-shaped bodies as the packing material.
In this embodiment, since the attachment filter having a sedimentation section has a radial ring-shaped thread structure, solids suspended in waste water can be attached to this radial ring-shaped thread structure and then digested, thereby reducing the genesis sludge capacity.
Since the radial ring-shaped thread structure is a thread-like packing material, the surface area is markedly large and thus suspended solids and microorganisms are easily attached thereon. Therefore, microorganisms are easily propagated and organic matters can also be treated. Furthermore, oxygen is not spread in the central portion of the radial ring-shaped thread structure, anaerobic microorganisms are propagated and can digest attached suspended solids.
In one embodiment of the present invention, the material of the radial ring-shaped thread structure is polyvinylidene chloride, polypropylene or vinylon.
According to this embodiment, the material of the radial ring-shaped thread structure is polyvinylidene chloride, polypropylene or vinylon. Due to its chemical resistance, not only the structure is not worn out, but can be semipermanently and easily secured at a low cost. Furthermore, the structure is also easily installed due to its light weight.
In one embodiment of the present invention, a coagulating sedimentation device having a sedimentation section is included; and
the attachment filter is installed in the subsequent stage of the coagulating sedimentation device.
According to this embodiment, a coagulating sedimentation device having a sedimentation section is included; and
the attachment filter is installed in the subsequent stage of the coagulating sedimentation device.
A fine pin floc originating in a coagulant after coagulating sedimentation can be treated by these attachment filter and rapid filter without consuming a large amount of electrical energy.
In one embodiment of the present invention, the coagulating sedimentation device is included; and
the attachment filter having a sedimentation section and the rapid filter are installed in the subsequent stage of the coagulating sedimentation device.
According to this embodiment, the attachment filter having a sedimentation section and the rapid filter are installed in the subsequent stage of the coagulating sedimentation device. Therefore, a fine pin floc originating in a coagulant after coagulating sedimentation can be treated by these attachment filter and rapid filter without consuming a large amount of electrical energy. At the same time, genesis sludge capacity is small as compared to a case where the rapid filter is solely installed.
In one embodiment of the present invention, a biological treatment device is included; and
the attachment filter having a sedimentation section is installed in the subsequent stage of the biological treatment device.
According to this embodiment, the attachment filter having a sedimentation section is installed in the subsequent stage of the biological treatment device. Therefore, a fine pin floc originating in a coagulant after coagulating sedimentation can be treated by this attachment filter without consuming a large amount of electrical energy.
In one embodiment of the present invention, a biological treatment device is included; and
the attachment filter and the rapid filter are installed in the subsequent stage of the biological treatment device.
According to this embodiment, the attachment filter and the rapid filter are installed in the subsequent stage of the biological treatment device. Therefore, a fine pin floc originating in microorganisms after biological treatment can be reliably and precisely treated by using the attachment filter and the rapid filter. At the same time, genesis sludge capacity is small as compared to a case where the rapid filter is solely installed.
In one embodiment of the present invention, a neutralization device is included; and
the attachment filter is installed in the subsequent stage of the neutralization device.
According to this embodiment, the attachment filter is installed in the subsequent stage of the neutralization device. Therefore, a fine pin floc generating in neutral products after neutralization can be treated by using these attachment filter and rapid filter without consuming a large amount of electrical energy.
In one embodiment of the present invention, a neutralization device is included; and
the attachment filter having a sedimentation section and the rapid filter are installed in the subsequent stage of the neutralization device.
According to this embodiment, the attachment filter having a sedimentation section and the rapid filter are installed in the subsequent stage of the neutralization device. Therefore, a fine pin floc generating in neutral products after neutralization can be treated by using these attachment filter and rapid filter without consuming a large amount of electrical energy. At the same time, genesis sludge capacity is small as compared to a case where the rapid filter is solely installed.
In one embodiment of the present invention, activated carbon is attached to the packing material composed of the radial ring-shaped thread structures.
According to this embodiment, activated carbon is attached to the packing material composed of the radial ring-shaped thread structures. Therefore, a surfactant in waste water is first adsorbed to activated carbon and then the surfactant can be adsorbed by microorganisms propagated on the activated carbon and the radial ring-shaped body.
The activated carbon exert a decolorizing function and a function for adsorbing organic matters, which are original functions of activated carbon. As a result, two functions, that is, an organic matter treating function of microorganisms propagated on the radial ring-shaped thread structure, which is a packing material, and a physical adsorbing function of activated carbon, can be exerted.
In one embodiment of the present invention, the attachment filter has either air washing equipment or water jet washing equipment or both of them for washing the packing material; and
the packing material is backwashed by air or water jet or both of them.
In this embodiment, backwash of the attachment filter having a sedimentation section can be performed by air, water jet or both of them. Therefore, when a large amount of sludge is generated, the generated sludge can be removed by backwash and then sedimented and removed from the sedimentation section.
In one embodiment of the present invention, waste water to be treated contains a surfactant.
According to this embodiment, waste water to be treated contains a surfactant. Therefore, the dissolved surfactant can be efficiently treated with the radial ring-shaped body wherein activated carbon is widely attached and distributed.
In one embodiment of the present invention, solids suspended in waste water are attached to a packing material and the solids attached to the packing material are sedimented to treat the waste water.
In this embodiment, solids suspended in the waste water are attached to the packing material and the particle sizes are increased. Then, the solids are further digested and reduced. The solids attached to the packing material are sedimented, separated and removed. Therefore, solids suspended in waste water can be filtered without consuming a large amount of electrical energy and the amount of waste can be reduced. Furthermore, the generated sludge is sedimented in the sedimentation section and removed from the sedimentation section. Thus, waste water can be treated.